This is a story about dimensions. Not those prissy metric Euro-numbers but good old American inch designations and a very specific and very Yankee one: the .45. Since around the middle of the 19th century, Americans have had a particular love affair with the .45 and people worldwide connect the .45 with America.

Of course, motion pictures and the pervasiveness of the cowboy films have a lot to do with this. Right from the beginning--correct or not--the Colt .45 Single Action Army revolver became a staple cinema prop. The fact that the gun was also made in a number of other calibers is beside the point; it was the .45 that became the star. Why this should be is conjectural. Of course, it was a military round, and until the advent of the .357 Magnum in 1935 it was the most potent commercial round--and for a long time it was the largest (diameter wise) revolver round loaded in any quantity in the U.S. Bigger is better, I suppose.

Over the years, scads of .45s have been developed and produced in the United States. Some, such as the .45 Colt, .45 ACP, .45-70, .454 Casull, .450 Marlin and .458 Winchester Magnum, became mainstays and true cartridge classics. Others, like the .45 Schofield (which, to be fair, has had a modest resurgence with Cowboy Action shooters), .45 Auto Rim, .45 Remington, .45 Winchester Magnum, .45 Super, .45 Silhouette, .451 Detonics, .450 Ackley Magnum, .45-60 Winchester, .45-120 Sharps and others either became obsolete or were relegated to use in specialty firearms. You may notice that we left out one newcomer, the .45 GAP. This .45 ACP variant is receiving mixed reviews, and it is really too early to tell just what category it will ultimately fit into.

In the meantime, let's take a look at five of the most popular .45s (in chronological order, of course) and see just where they fit into the scheme of things historically and ballistically.

The .45 lends itself to both auto and revolver handgun rounds. From left: .454 Casull, .45 Colt, .45 Schofield, .45 ACP and .45 GAP. Some of these loads—such as the.45 ACP, .45 Colt and .454 Casull—are also used in long guns.

.45 COLT
Many shooters still like to call this round the .45 "Long Colt" to differentiate it from its shorter .45 Schofield relative. The fact is that while there really were .32, .38 and .41 Long (and Short) Colt cartridges, the .45 Colt was never officially called anything other than .45 Colt.

The .45 Colt was adopted by the United States military in 1873 to be partnered with the now-legendary Colt Single Action Army revolver. As originally issued, the centerfire cartridge had a case length of 1.29 inches and fired a 255-grain lead bullet backed by 40 grains of black powder, producing a muzzle velocity of some 810 fps for a muzzle energy of around 380 ft.-lbs.

This was a pretty substantial cartridge when you realize that its closest military competitors of the period, such as the French 11mm Ordnance revolver (180-grain bullet at 195 ft.-lbs.), the British .450 Adams (225 grains, 211 ft.-lbs.) and the 10.6mm German Ordnance round (250 grains, 256 ft.-lbs.), were not in the same league. Even the much vaunted, behemoth 11.3mm Austro-Hungarian/Montenegrin Gasser revolver load, which had a case length of almost 1 1/2 inches, pushed its 302-grain bullet out at only 689 fps and produced a muzzle energy of 318 ft.-lbs. Nope, by the third quarter of the 19th century the .45 Colt was tops.